Triglycine sulfate

Introduction - pure and doped Triglycine Sulfate

Names
IUPAC name Glycine sulfate (3:1)
Other names Glycine sulfate; TGS
Identifiers
CAS Number	513-29-1 Y
3D model (JSmol)	Interactive image
ChemSpider	10111
ECHA InfoCard	100.007.414
EC Number	208-154-2
PubChem CID	10551
UNII	NEQ4Q0R0YA Y
CompTox Dashboard (EPA)	DTXSID40883415
InChI InChI=1S/3C2H5NO2.H2O4S/c3*3-1-2(4)5;1-5(2,3)4/h3*1,3H2,(H,4,5);(H2,1,2,3,4)
SMILES O=C(O)CN.O=S(=O)(O)O.O=C(O)CN.O=C(O)CN
Properties
Chemical formula	C6H17N3O10S
Molar mass	323.27 g·mol−1
Appearance	White powder
Density	1.69 g/cm3[1]
Structure
Crystal structure	Monoclinic
Space group	P21[2]
Lattice constant	a = 0.9417 nm, b = 1.2643 nm, c = 0.5735 nm α = 90°, β = 110°, γ = 90°
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Triglycine sulfate (TGS) is a chemical compound with a formula (NH₂CH₂COOH)₃·H₂SO₄. The empirical formula of TGS does not represent the molecular structure, which contains protonated glycine moieties and sulfate ions. TGS with protons replaced by Deuterium is called Deuterated TGS or DTGS; alternatively, DTGS may refer to doped TGS. By doping the DTGS with an amino acid L-Alanine, the crystal properties are improved and the new material is called Deuterated L-Alanine doped Triglycine Sulfate (DLATGS). TGS, DTGS, and DLATGS crystals are pyroelectric and ferroelectric and have been used as detector elements in infrared spectroscopy. TGS detector has been used as the target in vidicon cathode ray imager tubes. DTGS and DLATGS detectors have been used in many applications including Fourier-transform infrared spectroscopy (FTIR) devices and night vision.^[3]

Crystal structure and properties[]

Crystal structure of TGS. Hydrogen atoms are not shown.^[2]

TGS crystals may be formed by evaporation of an aqueous solution of sulfuric acid, which is containing a greater than three-fold excess of glycine.^[4] They belong to the polar space group P2₁ and therefore are pyroelectric and ferroelectric at room temperature, exhibiting spontaneous polarization along the b-axis ([010] direction). The Curie temperature of the ferroelectric transition is 49 °C for TGS and 62 °C for DTGS. The crystal structure consists of SO₄²⁻, 2(N⁺H₃CH₂COOH) (G1 and G2 in the crystal-structure diagram), and ⁺NH₃CH₂COO⁻ (G3) species held together by hydrogen bonds.^[5] These bonds are easily broken by the polar molecules of water that explains the hygroscopicity of TGS – its crystals are easily etched by water. Along the b-axis, the G1-SO₄ and G2-G3 layers are stacked alternately. The nearest two neighboring layers with identical chemical composition are rotated 180° around the b-axis against each other.^[2][6] DTGS and DLATGS materials are developed based TGS crystal and they have better pyroelectric properties and less noise as can be shown in Table 1 below.

Table 1: Ferroelectric properties of pure and doped triglycine sulfate crystal^{[7],[8],[9][10][11][12]}

Typical Performance of DLATGS Detectors[]

The typical performance and pyroelectric properties of DLATGS detectors of 1.3 and 2.0 mm in diameter of the element size are shown in Table 2 below.^[13][14][15]

Table 2: Typical performance and pyroelectric properties of DLATGS detector

References[]