In episode 22 of Mirai Nikki after Aru kissed Yukiteru, a angry Yuno runs and attacks Aru who slices/breaks her future diary in half. I definitely heard the phone go static which indicates when a future is changing, so my question is why didn't she die?
Well actually I do not watch the anime, but I searched and found people said the anime pretty much the same with the manga. So, what happened was...
Well, you know that the present Yuno is First World Yuno right? When she came to the present world (Second World), she killed the Second World Yuno, took her place in the present, and took her phone, and that made her having two phones. The phone that Aru destroyed was the phone that originally owned by Second World Yuno. Meanwhile, the real phone of First World Yuno was safe with her. That's why she didn't die.
For complete information, you can read Mirai Nikki's Wikia Page of Yuno. Read "The End Begins" and "The Final Battle" section.