Polar Oxysulfide for Nonlinear Optical Applications

Patent metadata

Field	Value
Publication number	US-2020392011-A1
Application number	US-202016918155-A
Country	US
Kind code	A1
Filing date	Jul 1, 2020
Priority date	Sep 5, 2018
Publication date	Dec 17, 2020
Grant date	—

Abstract

Single crystals of a new noncentrosymmetric polar oxysulfide SrZn2S2O (s.g. Pmn21) grown in a eutectic KF-KCl flux with unusual wurtzite-like slabs consisting of close-packed corrugated double layers of ZnS3O tetrahedra vertically separated from each other by Sr atoms and methods of making same.

First claim

What is claimed is:

1 . A new zinc oxysulfide compound comprising;
a noncentrosymmetric crystalline structure with chemical formula SrZn 2 S 2 O; lattice parameters of α=3.87440(10) Å, b=9.9847(3) Å, and c=6.0916(2) Å; and corrugated double layers of ZnS 3 O tetrahedra vertically separated by Sr 2+ ions.

2 . The new zinc oxysulfide compound of claim 1 , wherein an O/S anion ordered arrangement provides two distinct orientations of the ZnS 3 O tetrahedra.

3 . The new zinc oxysulfide compound of claim 1 , wherein the compound crystalizes in noncentrosymmetric polar space group Pmn2 1 .

4 . The new zinc oxysulfide compound of claim 1 , wherein an O/S anion ordered arrangement yields two distinct orientations of the Zn-centered tetrahedra.

5 . The new zinc oxysulfide compound of claim 1 , wherein the compound forms colorless, transparent crystals.

6 . The new zinc oxysulfide compound of claim 1 , having a band gap of 3.86 eV.

7 . The new zinc oxysulfide compound of claim 1 , wherein the compound is stable up to 650° C. in O 2 gas atmosphere.

8 . The new zinc oxysulfide compound of claim 1 , wherein the compound is phase matchable with twice a SHG intensity of potassium dihydrogen phosphate (KDP).

9 . The new zinc oxysulfide compound of claim 1 , wherein the compound has a Sr:Zn:S molar ratio of approximately 1.0:2.0:2.3.

10 . The new zinc oxysulfide compound of claim 1 , wherein the compound has a band gap energy of 3.86 eV.

11 . The new zinc oxysulfide compound of claim 1 , wherein temperatures greater than 1000° C. decompose the SrZn 2 S 2 O compound

12 . A method for synthesizing the compound SrZn 2 S 2 O comprising:
employing a molten salt method using a eutectic KF-KCl mixture; loading a silver tube with 1 mmol of SrO, 1 mmol of Zn, 1 mmol of S, 3.4 mmol of KF, and 4.1 mmol of KCl; placing the silver tube in a silica tube that was evacuated to 10 −4 Pa and sealed; and heating the silver tube in a tube furnace to 900° C. at 5° C./min, held for 24 h, and cooled to 600° C. at 0.17° C./min.

13 . The method of claim 12 , further comprising, extracting the compound from flux by dissolving the flux in water followed by sonication.

14 . A method for solid state synthesis of SrZn 2 S 2 O comprising:
mixing SRO, Zn and S in a stoichiometric ratio in an agate mortar to form a mixture; pressing the mixture into a pellet; heating the pellet in an evacuated silica tube at 1000° C. for 24 hours; and sonicating at 1000° C. with water.

Assignees

• Univ South Carolina
• Nat Inst Materials Science

Inventors

• Zur Loye Hans-Conrad
• Tsujimoto Yoshihiro

Classifications

• C01P2006/37

  Stability against thermal decomposition · CPC title

• C01P2002/77

  by unit-cell parameters, atom positions or structure diagrams · CPC title

• C01P2002/88

  by thermal analysis data, e.g. TGA, DTA, DSC · CPC title

• G02F1/37

  for second-harmonic generation {(G02F1/3532 takes precedence)} · CPC title

• G02F1/3551

  Crystals · CPC title