Aramaic in the Bible

“a great part of the book is written, not in Hebrew, but in Aramaic (2:4-7:28). In this respect Daniel is similar to Ezra, which is also partly written in Aramaic (4:8-6:18 and 7:12-26).” (source 7th Day Adventist site)

why did Daniel use Hebrew in 1:1-2:3 and chapter 8-12 and Aramaic in the center section?

In Aramaic:

Daniel 1:1-2:3 (Hebrew)
Daniel 2:4 - 7:28 (Aramaic)
Daniel 8-12 (Hebrew)
Ezra 4:8 - 6:18 (Aramaic)
Ezra 7:12-26 (Aramaic)

Jeremiah 10:11, and two words in Genesis 31:47.

One reason the critics accept the Aramaic of Ezra and not Daniel is because there is no supernatural predictive prophecy in Ezra. (source)