Process for preparing ceramics, ceramics thus obtained and uses thereof, especially as a sputtering target

Patent metadata

Field	Value
Publication number	US-10144674-B2
Application number	US-201514808437-A
Country	US
Kind code	B2
Filing date	Jul 24, 2015
Priority date	May 18, 2006
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method for preparing a ceramic from an inorganic base material in the form of a powder with a high boiling point, including a step in which the powder of the inorganic base material is mixed with a second inorganic component which is also in powder form and which serves as a dopant for the inorganic base material. The dopant comprises a single inorganic material or a mixture of at least two inorganic materials that have a dopant effect on the inorganic base material. The method also includes a sintering step performed at a high temperature. Owing to the high density thereof, the resulting ceramics are suitable for use as a target element. The films and electrodes obtained from said ceramics have particularly beneficial properties.

First claim

The invention claimed is:

1. A ceramic having an inorganic base material doped by an element J and being represented by the formula (I)
E α−x′ k J x′ m O β−x′(k−m)/2 2− □ x′(k−m)/2

wherein:
E α k O β 2− denotes the inorganic base material:
E denotes at least one metal from groups I to VIII of the Periodic Table of the Elements, and k denotes the average degree of oxidation of E in the formula I;
J denotes at least one metal from groups I to VIII of the Periodic Table of the Elements, and m denotes the average degree of oxidation of the element J, m<k;
α, k and β are positive numbers being between 1 and 20, such that αk−2β=0;
x′ denotes a positive integer such that x′<α; and
□ represents an anionic vacancy;
wherein a size of the pores present in the ceramic, measured by the high-resolution SEM method, is between 0.1 and 0.8 micrometers; and
wherein said ceramic is obtained by a process comprising:
a step of mixing the inorganic base material in powder form with an inorganic dopant material in powder form; and
a sintering step carried out at a temperature above 800° C., wherein the forces exerted on the powders, before the sintering step are less than or equal to 5 kg/cm 2 .

2. The ceramic according to claim 1 , having a crystallinity which, measured according to the X-ray diffraction method, corresponds to a crystallite size between 100 and 200 nm.

3. The ceramic according to claim 1 , having a conductivity which, measured according to the four-point method, and as a function of the temperature varying from 4.2 K to ambient temperature, is between 200 and 10000 siemens per cm.

4. The ceramic according to claim 1 , having a charge mobility which, measured according to the Seebeck effect method, is between 0.01 and 300 cm 2 /vol·s −1 .

5. The ceramic according to claim 1 , containing In 2 O 3 as inorganic base material, SnO 2 and ZnO as inorganic dopant material, the amount of SnO 2 and ZnO being between 3 and 15 mol. %, the amount of ZnO being greater than or equal to that of SnO 2 , said ceramic having:
an electrical conductivity between 300 and 500 S/cm;
a density between 6 and 7.1 g/cm 3 ;
a (total) surface area between 1 and 1000 cm 2 ; and
a percentage of irregularities between 5 and 20%.

6. A process for preparing a film, consisting in subjecting a target formed by a ceramic according to claim 1 to a RF or DC cathodic sputtering.

7. A film obtained by the process according to claim 6 , from a target made of a conductive ceramic having the formula In 1.805 Sn 0.095 Zn 0.10 O 3−δ with δ being between 0.001 and 0.03 or the formula In 1.94 Zn 0.06 O 2.97 , or from a target made of an insulating ceramic having one of the formulae Li 4 Ti 4.5 Mg 0.5 O 11.5 , Li 4 Ti 4.5 Zn 0.5 O 11.5 or Li 4 Ti 4.5 Ni 0.5 O 11.75 .

8. The ceramic according to claim 1 , wherein said ceramic has at least one of the following properties:
a macroscopic electrical conductivity, measured according to the four-point method (four-probe measurements) with a Keithley device (model 2400 Source Meter), which is greater than 300 siemens per cm;
an improved apparent density, measured according to the mercury porosimeter method, which is greater than 5 g/cm 3 ;
a (total) surface area greater than 5 cm 2 ;
an improved percentage of grain boundary irregularities, measured according to the high-resolution electron microscopy method, which is less than 30% of that of a corresponding ceramic prepared without addition of element.

9. A ceramic having an inorganic base material doped by an element J and being represented by the formula (I)
E α−x′ k J x′ m O β−x′(k−m)/2 2− □ x′(k−m)/2

wherein:
E α k O β 2− denotes the inorganic base material:
E denotes at least one metal from groups I to VIII of the Periodic Table of the Elements, and k denotes the average degree of oxidation of E in the formula I;
J denotes at least one metal from groups I to VIII of the Periodic Table of the Elements, and m denotes the average degree of oxidation of the element J, m<k;
α, k and β are positive numbers being between 1 and 20, such that αk−2β=0;
x′ denotes a positive integer such that x′<α; and
□ represents an anionic vacancy;
wherein the inorganic dopant material comprises SnO 2 and ZnO, the amount of SnO 2 and ZnO being between 3 and 15 mol. %, the amount of ZnO being greater than that of SnO 2 ;
wherein the molar ratio of the inorganic dopant material to the inorganic base material varies between 0.001 and 0.4; and
wherein said ceramic is obtained by a process comprising:
a step of mixing the inorganic base material in powder form with an inorganic dopant material in powder form; and
a sintering step carried out at a temperature above 800° C., wherein the forces exerted on the powders, before the sintering step are less than or equal to 5 kg/cm 2 .

10. The ceramic according to claim 9 , wherein the amount of ZnO is between 6 and 10 mol %.

11. The ceramic according to claim 9 , wherein the ceramic has the formula In 1.805 Sn 0.095 Zn 0.10 O 3−δ or the formula In 1.812 Sn 0.090 Zn 0.098 O 3−δ/2 with δ being between 0.001 and 0.03.

12. The ceramic according to claim 9 , wherein the ceramic is characterized by a crystalline bixbyite structure.

Assignees

• Hydro Quebec
• Centre Nat Rech Scient

Inventors

• Campet Guy
• Saadeddin Iyad
• Zaghib Karim

Classifications

• C04B2235/3286

  Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate · CPC title

• C04B2235/6567

  Treatment time · CPC title

• C23C14/3414

  Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy · CPC title

• C04B2235/6565

  Cooling rate · CPC title

• C04B35/6261 Primary

  Milling · CPC title