Hafnium

178.48

About Hafnium

In 1869, Dmitri Mendeleev’s periodic table predicted the existence of an element with 72 protons that would be chemically similar to zirconium . Though Henry Moseley and Niels Bohr’s subsequent theoretical models of the elements supported this prediction, it was not until 1923 that Georg von Hevesy and Dirk Coster provided the first empirical evidence of the elusive element 72, the penultimate element with stable isotopes to be discovered (followed by rhenium two years later). While working at the Bohr Institute of Theoretical Physics in Copenhagen, the two chemists identified the new element via x-ray spectroscopy analysis of a zirconium ore and named it "hafnium" after Hafnia, the Latin name for Copenhagen.

True to Mendeleev’s theory, Hafnium is extremely similar to zirconium; with nearly identical atomic radii, the two always occur together in nature in a continuous solid-solution and are two of the most difficult elements to separate. Primarily zirconium-based minerals typically contain 1-3% hafnium, the most common (and the subject of Coster and von Hevesy’s experiment) being zircon (zirconium silicate) with up to 4% hafnium by content. Other such zirconium-rich minerals include eudialyte, thortveitite, cyrtolite, armstrongite, alvite, and hafnon; the two elements can also be found in minerals such as the titanium ores ilmenite and rutile. Hafnium metal is primarily obtained as a byproduct of producing high-purity nuclear grade zirconium metal. The metals are typically chemically separated via a liquid-liquid extraction process that utilizing the slightly different solubilities of the two metals’ salts.

In its elemental form, hafnium is a ductile gray metal with a brilliantly lustrous silver sheen. Exposure to air causes the metal to form an impenetrable oxide film on its surface which lends the metal an extremely high resistance to corrosion and attack by most acids and alkalis. Because Hafnium’s melting point is high among its fellow transition metals, it is occasionally classified as a refractory metal. Like many other metals, hafnium as a fine powder is pyrophoric, meaning that it can ignite in air; for this reason, it is considered a hazardous material despite being non-toxic to humans. Thought hafnium shares many chemical and physical properties with zirconium, the two metals differ significantly in their densities (hafnium being roughly twice as dense) and their nuclear properties. Hafnium is an excellent neutron absorber with a high thermal neutron cross section, about 600 times that of zirconium, and one of its primary commercial uses is in control rods of nuclear reactors. It has also been used to enhance radiotherapy in the treatment of cancer.

Compound and alloy forms of hafnium are notable for their refractory properties. The melting points of several hafnium compounds are unparalleled within their respective groups: hafnium nitride’s (3310 °C) is the highest of any nitride, hafnium carbide’s (3890 °C) is the highest of any known binary compound, and tantalum hafnium carbide’s (4215 °C) is the single highest of any known compound. Thus, forms of hafnium are frequently employed in high-temperature environments as components of furnace linings, ceramics, rocket thrusters and jet engines for the aerospace industry, nozzle tips for plasma arc cutting, and wear resistant coatings. High performance superalloys typically contain hafnium in combination with metals like titanium, tungsten, and niobium; the metal improves creep ductility, strengthens grain boundaries, and increases corrosion resistance. Other applications for hafnium include serving as an oxygen and nitrogen “getter” in vacuum tubes and incandescent lighting, in geological dating (as isotopes), and in organic catalysis. Additionally, compounds like hafnium oxide and hafnium silicate have shown great promise as high-k dielectric materials that increase efficiency of semiconductor devices such as integrated circuits and transistors in the field of advanced microelectronics.

Products

Compounds

Alloys

Oxide Forms

Organometallics

Nanomaterials

Semiconductor & Optical

Isotopes

Hafnium-180 Oxide Isotope

There are relatively few technical uses for hafnium and, due to its ability as a nuclear "getter" or absorber of neutrons, much of the hafnium that is produced is used in control rods for nuclear reactors. Hafnium is also used in iron, titanium, niobium, tantalum, and other alloys. Hafnium is replacing polysilicon as the principle gate or electrode material in metal-oxide semiconductor field effect transistors (MOSFETs), which are the basis for all modern semiconductors. As semiconductors get smaller, the limiting factor in further size reduction has been the ability of the silicon dioxide gate to perform below 10 angstroms where leakage occurs. Recent research has been devoted to the development of high-k materials which can function as a di-electric barrier or gate with lower leakage. Using hafnium based alloys as this di-electric gate has allowed for the development of MOSFET gates smaller than 10 angstroms. This allows for further size reduction, reduced switching power requirements and improved performance. Hafnium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms of hafnium include pellets, rod, wire and granules for evaporation source material purposes. Hafnium nanomaterials provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Hafnium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Hafnium is also available in soluble forms including chloride, nitrate and acetate. These compounds can be manufactured as solutions at specified stoichiometries.

Hafnium Properties

Hafnium(Hf) atomic and molecular weight, atomic number and elemental symbol Hafnium is a Block D, Group 4, Period 6 element. The number of electrons in each of Hafnium's shells is 2, 8, 18, 32, 10, 2 and its electronic configuration is [Xe] 4f¹⁴ 5d² 6s². Hafnium Bohr Model In its elemental form, CAS 7440-58-6, hafnium has a steel gray appearance. Hafnium does not exist as a free element in nature. It is found in zirconium compounds such as zircon (ZrSiO₄). Hafnium was first predicted by Dmitri Mendeleev in 1869 but it was not until 1922 that it was first isolated Dirk Coster and George de Hevesy.

General Properties

Symbol:	Hf
Atomic Number:	72
Atomic Weight:	178.49
Element Category:	transition metal
Group, Period, Block:	4, 6, d
Color:	silvery/ gray steel
Other Names:	Afnio, Háfnio, Hafnio

Physical Properties

Melting Point:	2233 °C, 4051 °F, 2506 K
Boiling Point:	4603 °C,8317 °F, 4876 K
Density:	13.31 kg·cm³
Liquid Density @ Melting Point:	12 g·cm³
Density @ 20°C:	13.2 g/cm³
Density of Solid:	13310 kg·m³
Specific Heat:	0.14 (kJ/kg K)
Superconductivity Temperature:	0.128 [or -273.022 °C (-459.44 °F)] K
Triple Point:	N/A
Critical Point:	N/A
Heat of Fusion (kJ·mol^-1):	25.5
Heat of Vaporization (kJ·mol^-1):	570.7
Heat of Atomization (kJ·mol^-1):	618.9
Thermal Conductivity:	23.0 W·m^-1·K^-1
Thermal Expansion:	(25 °C) 5.9 µm·m^-1·K^-1
Electrical Resistivity:	(20 °C) 331 nΩ·m
Tensile Strength:	N/A
Molar Heat Capacity:	25.73 J·mol^-1·K^-1
Young's Modulus:	78 GPa
Shear Modulus:	30 GPa
Bulk Modulus:	110 GPa
Poisson Ratio:	0.37
Mohs Hardness:	5.5
Vickers Hardness:	1760 MPa
Brinell Hardness:	1700 MPa
Speed of Sound:	(20 °C) 3010 m·s^-1
Pauling Electronegativity:	1.3
Sanderson Electronegativity:	N/A
Allred Rochow Electronegativity:	1.23
Mulliken-Jaffe Electronegativity:	N/A
Allen Electronegativity:	N/A
Pauling Electropositivity:	2.7
Reflectivity (%):	N/A
Refractive Index:	N/A

Chemical Properties

Electrons:	72
Protons:	72
Neutrons:	106
Electron Configuration:	[Xe] 4f¹⁴ 5d² 6s²
Atomic Radius:	159 pm
Atomic Radius, non-bonded (Å):	2.23
Covalent Radius:	175±10 pm
Covalent Radius (Å):	1.64
Van der Waals Radius:	200 pm
Oxidation States:	4, 3, 2 (amphoteric oxide)
Phase:	Solid
Crystal Structure:	Hexagonal
Magnetic Ordering:	paramagnetic
Electron Affinity (kJ·mol^-1)	1.64
1^st Ionization Energy:	658.52 kJ·mol^-1
2^nd Ionization Energy:	1437.64 kJ·mol^-1
3^rd Ionization Energy:	2248.12 kJ·mol^-1

Identifiers

CAS Number:	7440-58-6
EC Number:	231-166-4
MDL Number:	MFCD00011032
Beilstein Number:	N/A
SMILES Identifier:	[Hf]
InChI Identifier:	InChI=1S/Hf
InChI Key:	VBJZVLUMGGDVMO-UHFFFAOYSA-N
PubChem CID:	23986
ChemSpider ID:	22422

Abundance

Earth - Total:	230 ppb
Mercury - Total:	177 ppb
Venus - Total:	241 ppb
Earth - Seawater (Oceans), ppb by weight:	0.008
Earth - Seawater (Oceans), ppb by atoms:	0.00028
Earth - Crust (Crustal Rocks), ppb by weight:	3300
Earth - Crust (Crustal Rocks), ppb by atoms:	380
Sun - Total, ppb by weight:	1
Sun - Total, ppb by atoms:	0.01
Stream, ppb by weight:	N/A
Stream, ppb by atoms:	N/A
Meterorite (Carbonaceous), ppb by weight:	170
Meterorite (Carbonaceous), ppb by atoms:	20
Typical Human Body, ppb by weight:	N/A
Typical Human Body, ppb by atom:	N/A
Universe, ppb by weight:	0.7
Universe, ppb by atom:	0.005

History

Discovered By:	Dirk Coster and George de Hevesy
Discovery Date:	1922
First Isolation:	Dirk Coster and George de Hevesy (1922)

Health, Safety & Transportation Information for Hafnium

Hafnium is not toxic; however, safety data for hafnium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Magnesium.

Safety Data
Material Safety Data Sheet	MSDS
Signal Word	Danger
Hazard Statements	H228
Hazard Codes	F
Risk Codes	11
Safety Precautions	N/A
RTECS Number	MG4600000
Transport Information	N/A
WGK Germany	nwg
Globally Harmonized System of Classification and Labelling (GHS)

Review and Print SDS for Hafnium Metal

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SAFETY DATA SHEET

Date Created: 05/15/2015

Date Revised: 05/15/2015

SECTION 1. IDENTIFICATION

Product Name: Hafnium Metal

Product Number: All applicable American Elements product codes, e.g. HF-M-02, HF-M-025, HF-M-03, HF-M-035, HF-M-04, HF-M-05

CAS #: 7440-58-6

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887

SECTION 2. HAZARDS IDENTIFICATION

Classification of the substance or mixture
Classification according to Regulation (EC) No 1272/2008
The product is not classified as hazardous to health or the environment according to the CLP regulation.
Classification according to Directive 67/548/EEC or Directive 1999/45/EC
Not applicable
Information concerning particular hazards for human and environment:
The product does not have to be labelled due to the calculation procedure of the "General Classification guideline for preparations of the EU" in the latest valid version.
Hazards not otherwise classified
No information known.
Label elements
Labelling according to Regulation (EC) No 1272/2008
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
WHMIS classification
Not controlled
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)
HEALTH
FIRE
REACTIVITY
0
0
0
Health (acute effects) = 0
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable

SECTION 3. COMPOSITION/INFORMATION ON INGREDIENTS

Chemical characterization: Mixtures
Dangerous components: Not applicable
Additional information: None known.
Non-Hazardous Ingredients
7440-58-6 Hafnium 98.0%
7440-67-7 Zirconium 2.0%

SECTION 4. FIRST AID MEASURES

Description of first aid measures
General information
No special measures required.
After inhalation
Seek medical treatment in case of complaints.
After skin contact
Generally the product does not irritate the skin.
After eye contact
Rinse opened eye for several minutes under running water. If symptoms persist, consult a doctor.
After swallowing
If symptoms persist consult doctor.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.

SECTION 5. FIREFIGHTING MEASURES

Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Carbon dioxide
Water
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Metal oxide fume
Advice for firefighters
Protective equipment: No special measures required.

SECTION 6. ACCIDENTAL RELEASE MEASURES

Personal precautions, protective equipment and emergency procedures
Not required.
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow product to reach sewage system or any water course.
Do not allow to penetrate the ground/soil.
Methods and material for containment and cleaning up:
Pick up mechanically.
Prevention of secondary hazards:
No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.

SECTION 7. HANDLING AND STORAGE

Handling
Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Information about protection against explosions and fires:
No special measures required.
Conditions for safe storage, including any incompatibilities
Storage
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
Store away from halogens.
Store away from halocarbons.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.

SECTION 8. EXPOSURE CONTROLS/PERSONAL PROTECTION

Additional information about design of technical systems:
No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace:
7440-58-6 Hafnium (98.0%)
PEL (USA) Long-term value: 0.5 mg/m³ as Hf
REL (USA) Long-term value: 0.5 mg/m³ as Hf
TLV (USA) Long-term value: 0.5 mg/m³ as Hf
EL (Canada) Long-term value: 0.5 mg/m³ as Hf
EV (Canada) Long-term value: 0.5 mg/m³
7440-67-7 Zirconium (2.0%)
PEL (USA) Long-term value: 5 mg/m³ as Zr
REL (USA) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
TLV (USA) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
EL (Canada) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
EV (Canada) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as zirconium
Additional information: No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Maintain an ergonomically appropriate working environment.
Breathing equipment: Not required.
Protection of hands: Not required.
Penetration time of glove material (in minutes)
Not determined
Eye protection: Safety glasses
Body protection: Protective work clothing.

SECTION 9. PHYSICAL AND CHEMICAL PROPERTIES

Information on basic physical and chemical properties
General Information
Appearance:
Form: Solid in various forms
Color: Grey to silver
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 2227 °C (4041 °F)
Boiling point/Boiling range: 4603 °C (8317 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous): Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Product is not selfigniting.
Danger of explosion: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0 hPa
Density at 20 °C (68 °F): 13.31 g/cm³ (111.072 lbs/gal)
Relative density: Not determined.
Vapor density: Not applicable.
Evaporation rate: Not applicable.
Solubility in / Miscibility with Water: Insoluble
Partition coefficient (n-octanol/water): Not determined.
Viscosity:
dynamic: Not applicable.
kinematic: Not applicable.
Solvent content:
Organic solvents: 0.0 %
Solids content: 100.0 %
Other information
No further relevant information available.

SECTION 10. STABILITY AND REACTIVITY

Reactivity
No information known.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
No dangerous reactions known
Conditions to avoid
No further relevant information available.
Incompatible materials:
Halogens
Halocarbons
Hazardous decomposition products:
Metal oxide fume

SECTION 11. TOXICOLOGICAL INFORMATION

nformation on toxicological effects
Acute toxicity: No effects known.
LD/LC50 values that are relevant for classification: No data
Skin irritation or corrosion: Generally the product does not irritate the skin.
Eye irritation or corrosion: No irritant effect.
Sensitization: No sensitizing effects known.
Germ cell mutagenicity: No effects known.
Carcinogenicity: No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
Reproductive toxicity: No effects known.
Specific target organ system toxicity - repeated exposure: No effects known.
Specific target organ system toxicity - single exposure: No effects known.
Aspiration hazard: No effects known.
Subacute to chronic toxicity: No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.
The product is not subject to classification according to internally approved calculation methods for preparations

SECTION 12. ECOLOGICAL INFORMATION

Toxicity
Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.
Other adverse effects
No further relevant information available.

SECTION 13. DISPOSAL CONSIDERATIONS

Waste treatment methods
Recommendation
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Recommendation:
Disposal must be made according to official regulations.

SECTION 14. TRANSPORT INFORMATION

UN-Number
DOT, ADN, IMDG, IATA
Not applicable
UN proper shipping name
DOT, ADN, IMDG, IATA
Not applicable
Transport hazard class(es)
DOT, ADR, ADN, IMDG, IATA
Class
Not applicable
Packing group
DOT, IMDG, IATA
Not applicable
Environmental hazards:
Marine pollutant (IMDG):
No
Special precautions for user
Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information:
DOT
Marine Pollutant (DOT):
No
UN "Model Regulation":
-

SECTION 15. REGULATORY INFORMATION

Safety, health and environmental regulations/legislation specific for the substance or mixture
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
SARA Section 313 (specific toxic chemical listings)
None of the ingredients are listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
None of the ingredients are listed.
Prop 65 - Developmental toxicity
None of the ingredients are listed.
Prop 65 - Developmental toxicity, female
None of the ingredients are listed.
Prop 65 - Developmental toxicity, male
None of the ingredients are listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
None of the ingredients are listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on themarket and use must be observed.
None of the ingredients is listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
None of the ingredients is listed.
REACH - Pre-registered substances
All ingredients are listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.

16. OTHER INFORMATION

Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Hafnium Isotopes

Naturally occurring hafnium (Hf) has five stable isotopes: ¹⁷⁶Hf, ¹⁷⁷Hf, ¹⁷⁸Hf, ¹⁷⁹Hf, and ¹⁸⁰Hf.

Nuclide	Isotopic Mass	Half-Life	Mode of Decay	Nuclear Spin	Magnetic Moment	Binding Energy (MeV)	Natural Abundance (% by atom)
¹⁵³Hf	152.97069(54)#	400# ms [>200 ns]	Unknown	1/2+#	N/A	1183.2	-
¹⁵⁴Hf	153.96486(54)#	2(1) s	ß⁺ to ¹⁵⁴Lu; a to ¹⁵⁰Yb	0+	N/A	1200.6	-
¹⁵⁵Hf	154.96339(43)#	890(120) ms	ß⁺ to ¹⁵⁵Lu; a to ¹⁵¹Yb	7/2-#	N/A	1208.68	-
¹⁵⁶Hf	155.95936(22)	23(1) ms	a to ¹⁵²Yb; ß⁺ to ¹⁵⁶Lu	0+	N/A	1226.07	-
¹⁵⁷Hf	156.95840(21)#	115(1) ms	a to ¹⁵³Yb; ß⁺ to ¹⁵⁷Lu	7/2-	N/A	1234.15	-
¹⁵⁸Hf	157.954799(19)	2.84(7) s	ß⁺ to ¹⁵⁸Lu; a to ¹⁵⁴Yb	0+	N/A	1242.23	-
¹⁵⁹Hf	158.953995(18)	5.20(10) s	ß⁺ to ¹⁵⁹Lu; a to ¹⁵⁵Yb	7/2-#	N/A	1250.31	-
¹⁶⁰Hf	159.950684(12)	13.6(2) s	ß⁺ to ¹⁶⁰Lu; a to ¹⁵⁶Yb	0+	N/A	1258.39	-
¹⁶¹Hf	160.950275(24)	18.2(5) s	ß⁺ to ¹⁶¹Lu; a to ¹⁵⁷Yb	3/2-#	N/A	1266.46	-
¹⁶²Hf	161.94721(1)	39.4(9) s	ß⁺ to ¹⁶²Lu; a to ¹⁵⁸Yb	0+	N/A	1283.86	-
¹⁶³Hf	162.94709(3)	40.0(6) s	ß⁺ to ¹⁶³Lu; a to ¹⁵⁹Yb	3/2-#	N/A	1291.94	-
¹⁶⁴Hf	163.944367(22)	111(8) s	ß⁺ to ¹⁶⁴Lu	0+	N/A	1300.02	-
¹⁶⁵Hf	164.94457(3)	76(4) s	ß⁺ to ¹⁶⁵Lu	(5/2-)	N/A	1308.1	-
¹⁶⁶Hf	165.94218(3)	6.77(30) min	ß⁺ to ¹⁶⁶Lu	0+	N/A	1316.17	-
¹⁶⁷Hf	166.94260(3)	2.05(5) min	ß⁺ to ¹⁶⁷Lu	(5/2)-	N/A	1324.25	-
¹⁶⁸Hf	167.94057(3)	25.95(20) min	ß⁺ to ¹⁶⁸Lu	0+	N/A	1332.33	-
¹⁶⁹Hf	168.94126(3)	3.24(4) min	ß⁺ to ¹⁶⁹Lu	(5/2)-	N/A	1340.41	-
¹⁷⁰Hf	169.93961(3)	16.01(13) h	EC to ¹⁷⁰Lu	0+	N/A	1357.81	-
¹⁷¹Hf	170.94049(3)	12.1(4) h	ß⁺ to ¹⁷⁰Lu	7/2(+)	N/A	1356.57	-
¹⁷²Hf	171.939448(26)	1.87(3) y	EC to ¹⁷²Lu	0+	N/A	1373.96	-
¹⁷³Hf	172.94051(3)	23.6(1) h	EC to ¹⁷³Lu	1/2-	N/A	1372.73	-
¹⁷⁴Hf	173.940046(3)	2.0(4)E+15 y	a to ¹⁷⁰Yb	0+	N/A	1380.8	0.16
¹⁷⁵Hf	174.941509(3)	70(2) d	EC to ¹⁷⁵Lu	5/2-	0.54	1388.88	-
¹⁷⁶Hf	175.9414086(24)	Observationally Stable	-	0+	N/A	1396.96	5.26
¹⁷⁷Hf	176.9432207(23)	Observationally Stable	-	7/2-	0.7936	1405.04	18.6
¹⁷⁸Hf	177.9436988(23)	Observationally Stable	-	0+	N/A	1413.12	27.28
¹⁷⁹Hf	178.9458161(23)	Observationally Stable	-	9/2+	-0.6409	1421.2	13.62
¹⁸⁰Hf	179.9465500(23)	Observationally Stable	-	0+	N/A	1429.28	35.08
¹⁸¹Hf	180.9491012(23)	42.39(6) d	ß^- to ¹⁸¹Ta	1/2-	N/A	1437.36	-
¹⁸²Hf	181.950554(7)	8.90(9)E+6 y	ß^- to ¹⁸²Ta	0+	N/A	1436.12	-
¹⁸³Hf	182.95353(3)	1.067(17) h	ß^- to ¹⁸³Ta	(3/2-)	N/A	1444.2	-
¹⁸⁴Hf	183.95545(4)	4.12(5) h	ß^- to ¹⁸⁴Ta	0+	N/A	1452.28	-
¹⁸⁵Hf	184.95882(21)#	3.5(6) min	ß^- to ¹⁸⁵Ta	3/2-#	N/A	1460.35	-
¹⁸⁶Hf	185.96089(32)#	2.6(12) min	ß^- to ¹⁸⁶Ta	0+	N/A	1459.12	-
¹⁸⁷Hf	186.96459(43)#	30# s [>300 ns]	Unknown	N/A	N/A	1467.19	-
¹⁸⁸Hf	187.96685(54)#	20# s [>300 ns]	Unknown	0+	N/A	1475.27	-