Patent ID: 8197713

Claim:
A process for producing a fluorescent powder comprising an acicular or fibrous zinc oxide single crystal with an aspect ratio of 5 or higher, comprising: a step of producing a raw material solution selected from the group consisting of a raw material solution (A) that is a solution containing zinc ions and ions of dopant element, a raw material solution (B) that is an alkali solution containing zinc ions, and a mixed solution of the raw material solution (A) and the raw material solution (B); and a hydrothermal reaction step wherein a hydrothermal reaction of the raw material solution is carried out in a hermetically sealed vessel at a subcritical or supercritical pressure, wherein the hydrothermal reaction step is carried out at a temperature from 200° C. to 250° C. for 1 to 30 hours and subsequently carried out at a temperature from 400° C. to 600° C. for 30 minutes to 10 hours.