1. Particle or powder of a compound of formula Zn1\u2212yMyO1\u2212xSx, wherein:
x has a value in the range from 0.01 to 0.08,
M represents a divalent metal,
y has a value in the range from 0 to 0.2, and the compound has a wurtzite structure.
2. Particle or powder according to claim 1, wherein y has a value in the range from 0 to 0.0002.
3. Particle or powder according to claim 1, wherein x has a value in the range from 0.01 to 0.05.
4. Particle or powder according to claim 1, wherein the particle or powder is single-phase.
5. Particle or powder according to claim 1, wherein the particle has a particle size or the powder has a mean grain size of 300 nm or more.
6. Particle or powder according to claim 5, wherein the particle has a particle size or the powder has a mean grain size in the range from 1 to 500 \u03bcm.
7. Particle or powder according to claim 1, wherein M is selected from the group consisting of: Cr, Mn, Fe, Co, Ni, Cu, Cd and Mg.
8. Article comprising particles or powder according to claim 1.
9. Article according to claim 8, wherein the article comprises the particles or powder in the region of its surface, so that the particles or powder are able to develop a UV-absorbing action when the article is used.
10. Article according to claim 9, wherein the article is a cosmetic or pharmaceutical preparation, a plastics material, a paint or a surface coating.
11. Article according to claim 8, wherein the article comprises said particles or powder in an antimicrobially effective amount andor in an amount that promotes the healing of wounds.
12. An ultraviolet light absorbent composition comprising a particle or powder according to claim 1.
13. Process for the preparation of powders according to claim 1, comprising the following step:
heating ZnO and ZnS together in the presence of a halogen or halogen compound.
14. Process for the preparation of powders according to claim 13, comprising the following steps:
producing an aqueous suspension of zinc hydroxide,
contacting the zinc hydroxide with sulfide anions so that a reaction precipitate forms, and
subjecting the reaction precipitate to heat.
15. Method of absorbing UV radiation, comprising the following step:
exposing a particle or powder according to claim 1 to UV radiation.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A planar magnetic transducer for use with an acoustic speaker, the transducer including; a diaphragm mounted within a frame of a stator, a metallic electrical circuit pattern provided on a surface of said diaphragm at least a portion of which is spaced inwardly of said frame, at least one magnetic motor structure carried within said frame so as to be in spaced generally opposing relationship to said electrical circuit pattern within the stator, said at least one magnetic motor structure including a support member having a central portion and a pair of spaced angled portions, said angled portions supporting spaced magnet elements which are oriented generally at an angle relative to a plane of said diaphragm whereby when electrical power is supplied to said electrical circuit pattern said diaphragm is caused to vibrate by magnetic fields associated with said spaced magnets elements.
2. The planar magnetic transducer of claim 1 including at least one intermediate magnet element mounted between said spaced magnetic elements along said central portion of said support member.
3. The planar magnetic transducer of claim 2 wherein said spaced magnet elements are oriented generally toward one another and said at least one intermediate magnet element.
4. The planar magnetic transducer of claim 3 wherein said support member is formed of a metallic material of a type to function as a pole piece for said at least one magnetic motor.
5. The planar magnetic transducer of claim 3 wherein like poles of said spaced magnet elements are oriented generally toward said diaphragm.
6. The planar magnetic transducer of claim 5 wherein said spaced magnet elements are selected from a group of magnet elements consisting of rare earth permanent magnets.
7. The planar magnetic transducer of claim 1 wherein said central portion of said support member supports a central magnet element having a pole surface oriented toward said diaphragm and generally parallel to said plane of said diaphragm.
8. The planar magnetic transducer of claim 7 wherein said pole surface of said central magnet element is of a polarity opposite that of like pole surfaces of said spaced magnet elements which are oriented toward said diaphragm.
9. The planar magnetic transducer of claim 8 wherein said central and said spaced magnet elements are selected from a group of magnet elements consisting of rare earth permanent magnets.
10. The planar magnetic transducer of claim 8 wherein a volume defined by said central magnet element is greater than a volume defined by each of said spaced magnet elements.
11. The planar magnetic transducer of claim 8 including at least one magnetic motor structure carried with said frame such that at least one magnetic motor structure is provided on each of opposing sides of said diaphragm.
12. The planar magnetic transducer of claim 11 wherein said magnetic motor structures are mounted such that their respective central and spaced magnet elements are aligned with one another on said opposing sides of said diaphragm.
13. The planar magnetic transducer of claim 11 wherein said frame has a lower portion and an upper portion and side portions which taper toward one another from said lower portion to said upper portion.
14. A method of increasing the efficiency and lowering distortion of a diaphragm of a planar magnetic transducer having a diaphragm mounted within a stator frame and having an at least one electrical circuit trace pattern on a surface thereof; the method including establishing a magnetic field within the stator frame along at least on side of the diaphragm using spaced magnet elements having like poles which are oriented at an angle relative to a plane of the diaphragm and toward one another.
15. The method of claim 14 including an additional step of establishing the magnetic field through at least one central magnet element disposed intermediate said spaced magnet elements.
16. The method of claim 15 including establishing a magnetic field on opposite sides of the diaphragm.
17. The method of claim 16 including changing lines of flux within the magnetic fields by increasing a volume of the central magnet element relative to a volume of each of said spaced magnet elements.
18. An acoustical speaker incorporating the planar magnetic transducer of claim 1.
19. An acoustical speaker incorporating the planar magnetic transducer of claim 12.