Terbium participates in light-emitting materials and alloys that change length in a magnetic field. Combining terbium, dysprosium, and iron creates an example of converting magnetic changes into mechanical motion. Its other uses in optical materials connect that engineering behavior to interactions between matter and light.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How does a terbium phosphor turn supplied energy into green emission?
Terbium-containing phosphor or chelate
FOLLOW THIS RELATIONSHIP
Locate the active chemical form
Terbium is chemically bound within a phosphor host or chelate. The optically active environment differs from the arrangement in elemental terbium metal.
Explore the model (optional)
Spatial model
INTERACTIVE 3D36 visible sites
Terbium · an activator in a hostDrag to rotate · scroll or pinch to zoom
Phosphor host
An activator ion occupies a small fraction of sites in a host material. Select excitation to connect this arrangement to light emission.
What this representation means
Conceptual phosphor schematic, not a specific crystal structure, measured spectrum, or atomistic emission simulation. Color is an explanatory cue; host sites and concentration are illustrative.
Atomic identity, reference properties and structure models
INTERACTIVE 3D36 visible sites
Terbium · an activator in a hostDrag to rotate · scroll or pinch to zoom
Phosphor host
An activator ion occupies a small fraction of sites in a host material. Select excitation to connect this arrangement to light emission.
What this representation means
Conceptual phosphor schematic, not a specific crystal structure, measured spectrum, or atomistic emission simulation. Color is an explanatory cue; host sites and concentration are illustrative.
Ytterby chemistry, green light, and controlled motion
Carl Gustav Mosander announced terbium-bearing material in 1843 while investigating yttria, already known to conceal chemically similar rare earths. These early oxide fractions were not equivalent to modern pure metal. Terbium later became valuable for optical and magnetic materials: in 1985, NBS researchers examined terbium-chelate phosphors for postage-stamp applications. Its story runs from difficult separation to designing a recognizable signal in an everyday object.
1843
Terbium-bearing fraction identified
Mosander distinguished oxide material during investigations of yttria.
1985
Postal phosphors investigated
NBS studied degradation of terbium-chelate phosphors for stamp applications.
Terbium occurs alongside other rare-earth elements in minerals including monazite and euxenite. It must be separated from chemically similar companions before a specific material can be made. Its mineral origin is shared with several neighbors, but that does not make their optical signatures or magnetic-alloy effects interchangeable.
Terbium connects two striking behaviors that should be kept separate. Terbium in suitable phosphors can emit green light after excitation. In terbium–dysprosium–iron , magnetostriction converts a changing magnetic condition into a small change of shape. One process produces an optical signal; the other produces mechanical displacement.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
1629 K
at standard pressure unless noted
Boiling point in K
3503 K
101.325 kPa
Density in g/cm³
8.23 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
1.1 Pauling
Pauling scale
First ionization energy in kJ/mol
565.8 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
194 pm
single-bond covalent radius
Common oxidation states
+3
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
1.2 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1843 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 6
Tb 1.1 Pauling · Terbium
Electronegativity across period 6. Exact values.
Cs
0.79
Ba
0.89
La
1.1
Ce
1.12
Pr
1.13
Nd
1.14
Sm
1.17
Eu
1.2
Gd
1.2
Tb
1.1
Dy
1.22
Ho
1.23
Er
1.24
Tm
1.25
Yb
1.1
Lu
1.27
Hf
1.3
Ta
1.5
W
2.36
Re
1.9
Os
2.2
Ir
2.2
Pt
2.28
Au
2.54
Hg
2
Tl
1.62
Pb
2.33
Bi
2.02
Po
2
At
2.2
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
