Single-source synthesis of ceramic oxide nanoparticles
The tris(trimethylsilyl)silanol (H-SST) ligand can be reacted with a Group 4 or 5 metal alkoxides in a solvent to form an SST-modified metal alkoxide precursor. Exemplary Group 4 precursors include [Ti(SST) 2 (OR) 2 ] (OR=OPr i , OBu t , ONep); [Ti(SST) 3 (OBu n )]; [Zr(SST) 2 (OBu t ) 2 (py)]; [Zr(SST) 3 (OR)] (OR=OBu t , ONep); [Hf(SST) 2 (OBu t ) 2 ]; and [Hf(SST) 2 (ONep) 2 (py) n ] (n=1, 2), where OPr i =OCH(CH 3 ) 2 , OBu t =OC(CH 3 ) 3 , OBu n =O(CH 2 ) 3 CH 3 , ONep=OCH 2 C(CH 3 ) 3 , and py=pyridine. Exemplary Group 5 precursors include [V(SST) 3 (py) 2 ]; [Nb(SST) 3 (OEt) 2 ]; [Nb(O)(SST) 3 (py)]; 2[H][(Nb(μ-O) 2 (SST)) 6 (μ 6 -O)]; [Nb 8 O 10 (OEt) 18 (SST) 2 .⅕Na 2 O]; [Ta(SST)(μ-OEt)(OEt) 3 ] 2 ; and [Ta(SST) 3 (OEt) 2 ]; where OEt=OCH 2 CH 3 . When thermally processed, the precursors can form unusual core-shell nanoparticles. For example, HfO 2 /SiO 2 core/shell nanoparticles have demonstrated resistance to damage in extreme irradiation and thermal environments.
1. A method to synthesize a metal-siloxide precursor, comprising reacting tris(trimethylsilyl)silanol ligand (H-SST) with a Group 4 or 5 metal alkoxide in a solvent to form an SST-modified metal alkoxide precursor.
2. The method of claim 1 , wherein the Group 4 metal comprises Ti, Zr, or Hf.
3. The method of claim 1 , wherein the Group 5 metal comprises V, Nb, or Ta.
4. The method of claim 1 , wherein the alkoxide comprises OCH 2 CH 3 , OCHMe 2 , or OCMe 3 , or OCH 2 CMe 3 .
5. The method of claim 1 , wherein the solvent comprises toluene or pyridine.
6. The method of claim 2 , wherein the SST-modified metal siloxide precursor comprises [Ti(SST) 2 (OR) 2 ], wherein OR=OPr i , OBu t , or ONep; [Ti(SST) 3 (OBu n )]; [Zr(SST) 2 (OBu t ) 2 (py)]; [Zr(SST) 3 (OR)], wherein OR=OBu t or ONep; or [Hf(SST) 2 (OBu t ) 2 ]; [Hf(SST) 2 (ONep) 2 (py) n ], wherein n=1 or 2, and wherein OPr i =OCH(CH 3 ) 2 , OBu t =OC(CH 3 ) 3 , OBu n =O(CH 2 ) 3 CH 3 , ONep=OCH 2 C(CH 3 ) 3 , and py=pyridine.
7. The method of claim 3 , wherein the SST-modified metal siloxide precursor comprises [V(SST) 3 (py) 2 ]; [Nb(SST) 3 (OEt) 2 ]; [Nb(O)(SST) 3 (py)]; 2[H][(Nb(μ-O) 2 (SST)) 6 (μ 6 -O)]; [Nb 8 O 10 (OEt) 18 (SST) 2 ·⅕Na 2 O]; [Ta(SST)(μ-OEt)(OEt) 3 ] 2 ; or [Ta(SST) 3 (OEt) 2 ]; wherein OEt=OCH 2 CH 3 and py=pyridine.
8. A method of making a ceramic oxide nanoparticle comprising heating the SST-modified metal alkoxide precursor of claim 1 to above a decomposition temperature.
9. The method of claim 8 , wherein the decomposition temperature is greater than or equal to 450° C.
10. The method of claim 8 , wherein the ceramic oxide nanoparticle comprises a core-shell nanoparticle.
11. The method of claim 10 , wherein the core-shell nanoparticle comprises a silicate core and a metal oxide shell.
12. The method of claim 11 , wherein the metal oxide shell comprises ZrO 2 .
13. The method of claim 10 , wherein the core-shell nanoparticle comprises a metal oxide core and a silicate shell.
14. The method of claim 13 , wherein the metal oxide core comprises HfO 2 .
15. The method of claim 8 , wherein the ceramic oxide nanoparticle comprises TiO 2 , Ta 2 O 3 , Nb 2 O 3 , or V 2 O 3 .