In what English episode does Sailor moon first use crystal power?

Sailor Moon first uses Crystal Power in Episode 24, "The Dark Kingdom's Secret Weapon".

In this episode, she uses the power of the Silver Crystal to break free from the Dark Kingdom's control and defeat Queen Beryl.

However, it's important to note that she doesn't use the phrase "Crystal Power" specifically in this episode. She simply draws on the power of the Silver Crystal to transform and attack.